This invention relates to a metal aluminate catalyst support and to a process of making such metal aluminate catalyst support.
It is known that catalysts having a metal aluminate support, such as a zinc aluminate support, can be used in the selective hydrogenation and dehydrogenation of hydrocarbons. In general, prior art processes to produce such metal aluminate support typically involve physically mixing a metal component, such as metal oxide, and an aluminum component, such as aluminum oxide, followed by drying and calcining to produce a metal aluminate catalyst support containing a metal aluminate such as a zinc aluminate, also referred to as a zinc spinel. Another common process of producing such metal aluminate catalyst support comprises coprecipitating an aqueous solution of a metal component, such as metal nitrate, and an aqueous solution of an aluminum component, such as aluminum nitrate, followed by drying and calcining such as the process disclosed in U.S. Pat. No. 3,641,182. However, these processes are costly and time-consuming. Consequently, a process to produce a metal aluminate catalyst support which does not involve physical mixing or coprecipitation would be of significant contribution to the art and to the economy.
An object of the present invention is to provide a process to produce a metal aluminate catalyst support that does not involve the physical mixing of a metal component and an aluminum component.
Another object of the present invention is to provide a process to produce a metal aluminate catalyst support that does not involve a coprecipitation of a metal component and an aluminum component.
Yet another object of the present invention is to provide a process to produce a metal aluminate catalyst support that is economically cheaper and easier than prior art methods.
In accordance with one aspect of the present invention, there is provided a process to produce a metal aluminate catalyst support. Such process comprises incorporating alumina with a metal component, preferably impregnating alumina with a melted metal component, to thereby provide a metal-incorporated alumina followed by drying and high temperature calcining to thereby provide a metal aluminate catalyst support. Such metal aluminate catalyst support contains a metal aluminate similar to those metal aluminate catalyst supports produced by physically mixing a metal component, such as metal oxide, and an aluminum component, such as aluminum oxide, or coprecipitating a metal-containing solution and an aluminum-containing solution, followed by drying and calcining.
In accordance with another aspect of the invention, there is provided a metal aluminate catalyst support prepared by a process comprising impregnating alumina with a metal component, preferably a melted metal component, followed by drying and high temperature calcining.
In accordance with yet another aspect of the invention, there is provided a metal aluminate catalyst support.
Other objects and advantages of the invention will become more apparent from the detailed description of the invention and the appended claims.
It has been discovered that a metal aluminate catalyst support can be readily prepared from existing pre-formed alumina (also referred to as aluminum oxide) tablets, pellets, extrudates, spheres, and the like and combinations thereof by incorporating, preferably impregnating, such alumina with a metal component, preferably a melted metal component, followed by drying and then high temperature calcining. The resulting metal aluminate catalyst support contains a metal aluminate such as a zinc aluminate, also referred to as a zinc spinel, which is readily formed on the outside of, i.e., on the surface of, the alumina. Such metal aluminate catalyst support preparation is considerably cheaper and easier than preparation techniques involving physically mixing a metal component, such as metal oxide, and an aluminum component, such as aluminum oxide, or coprecipitating metal-containing and aluminum-containing solutions, followed by extended calcining and then pelletizing and/or extruding to form catalyst pellets or granules.
Generally, the alumina used in producing the metal aluminate catalyst support according to the inventive process(es) disclosed herein can be any suitable alumina such as, but not limited to, alpha alumina, beta alumina, delta alumina, eta alumina, gamma alumina, and the like and combinations thereof. Preferably, such alumina is gamma alumina. The alumina can also contain minor amounts of other ingredients, such as, for example, silica in a range of from about 1 weight percent silica to about 10 weight percent silica, which do not adversely affect the quality of the metal aluminate catalyst support. Generally, it is desirable to have an essentially pure alumina, preferably essentially pure gamma alumina, as a starting material for preparing the metal aluminate catalyst support. The starting alumina can be made by any manner or method(s) known in the art. As an example, a suitable commercially available starting alumina for use in preparing the metal aluminate catalyst support according to the inventive process(es) described herein are gamma alumina tablets or extrudate pellets or spheres such as those manufactured by UOP Inc., McCook, Ill., and Engelhard Company, Elyria, Ohio.
Alumina suitable for use in the inventive process(es) described herein can also be characterized by having the following characteristics. Generally, the surface area of the alumina is in the range of from about 5 m2/g (measured by the Brunauer, Emmett, Teller method, i.e., BET method) to about 400 m2/g, preferably in the range of from about 10 m2/g to about 300 m2/g and, most preferably, in the range of from 50 m2/g to 200 m2/g.
The pore volume of the alumina is generally in the range of from about 0.05 mL/g to about 2 mL/g, preferably in the range of from about 0.10 mL/g to about 1.5 mL/g and, most preferably, in the range of from 0.20 mL/g to 1 mL/g.
The average pore diameter of the alumina is generally in the range of from about 5 angstroms to about 600 angstroms, preferably in the range of from about 10 angstroms to about 500 angstroms and, most preferably, in the range of from 25 angstroms to 200 angstroms.
The alumina can have any suitable shape or form. Preferably such alumina is in the form of tablets, pellets, extrudates, spheres, and the like and combinations thereof. The alumina generally has a particle size in the range of from about 0.5 millimeters (mm) to about 10 mm, preferably in the range of from about 1 mm to about 8 mm and, most preferably, in the range of from 1 mm to 6 mm.
Any metal component which can form a spinel when utilized in accordance with the inventive process(es) disclosed herein can be used. Examples of a potentially suitable metal component for incorporating the metal of such metal component, preferably impregnating the metal of such metal component into, onto, or with the alumina to thereby provide a metal-incorporated alumina include, but are not limited to, a zinc component, a magnesium component, a calcium component, a barium component, a beryllium component, a cobalt component, an iron component, a manganese component, a strontium component, a lithium component, a potassium component, and the like and combinations thereof. Preferable examples of a potentially suitable metal component for incorporating the metal of such metal component, preferably impregnating the metal of such metal component into, onto, or with the alumina to thereby provide a metal-incorporated alumina include, but are not limited to, a zinc component, a magnesium component, a calcium component, and the like and combinations thereof. More preferably, such metal component is a zinc component.
Examples of a potentially suitable zinc component for incorporating zinc, preferably impregnating zinc into, onto, or with the alumina include, but are not limited to, zinc nitrate hexahydrate, zinc nitrate, hydrated zinc nitrate, zinc chloride, zinc acetate dihydrate, zinc acetylacetonate hydrate, zinc carbonate hydroxide monohydrate, zinc perchlorate hexahydrate, hydrated zinc sulfate, zinc sulfate monohydrate, zinc sulfate heptahydrate, and the like and combinations thereof. The preferred zinc component for incorporating zinc, preferably impregnating zinc into, onto, or with the alumina is hydrated zinc nitrate. The most preferred zinc component for incorporating zinc, preferably impregnating zinc into, onto, or with the alumina is zinc nitrate hexahydrate.
Examples of a potentially suitable magnesium component for incorporating magnesium, preferably impregnating magnesium into, onto, or with the alumina include, but are not limited to, magnesium nitrate hexahydrate, magnesium nitrate, hydrated magnesium nitrate, magnesium chloride, hydrated magnesium chloride, magnesium chloride hexahydrate, magnesium acetate tetrahydrate, magnesium acetylacetonate dihydrate, magnesium carbonate hydroxide pentahydrate, magnesium perchlorate, magnesium perchlorate hexahydrate, magnesium sulfate, magnesium sulfate heptahydrate, magnesium sulfate monohydrate, and the like and combinations thereof. The preferred magnesium component for incorporating magnesium, preferably impregnating magnesium into, onto, or with the alumina is hydrated magnesium nitrate. The most preferred magnesium component for incorporating magnesium, preferably impregnating magnesium into, onto, or with the alumina is magnesium nitrate hexahydrate.
Examples of a potentially suitable calcium component for incorporating calcium, preferably impregnating calcium into, onto, or with the alumina include, but are not limited to, calcium nitrate tetrahydrate, calcium nitrate, hydrated calcium nitrate, calcium chloride, hydrated calcium chloride, calcium chloride dihydrate, calcium chloride hexahydrate, calcium chloride hydrate, calcium acetate hydrate, calcium acetate monohydrate, calcium acetylacetonate hydrate, calcium perchlorate tetrahydrate, calcium sulfate, calcium sulfate dihydrate, calcium sulfate hemihydrate, and the like and combinations thereof. The preferred calcium component for incorporating calcium, preferably impregnating calcium into, onto, or with the alumina is hydrated calcium nitrate. The most preferred calcium component for incorporating calcium, preferably impregnating calcium into, onto, or with the alumina is calcium nitrate tetrahydrate.
Examples of a potentially suitable barium component for incorporating barium, preferably impregnating barium into, onto, or with the alumina include, but are not limited to, barium nitrate, hydrated barium nitrate, barium chloride, hydrated barium chloride, barium chloride dihydrate, barium acetate, barium acetylacetonate hydrate, barium carbonate, barium perchlorate, barium perchlorate trihydrate, barium sulfate, and the like and combinations thereof. The preferred barium component for incorporating barium, preferably impregnating barium into, onto, or with the alumina is hydrated barium nitrate. The most preferred barium component for incorporating barium, preferably impregnating barium into, onto, or with the alumina is barium nitrate.
Examples of a potentially suitable beryllium component for incorporating beryllium, preferably impregnating beryllium into, onto, or with the alumina include, but are not limited to, beryllium nitrate trihydrate, hydrated beryllium nitrate, beryllium chloride, hydrated beryllium sulfate, beryllium sulfate tetrahydrate, and the like and combinations thereof. The preferred beryllium component for incorporating beryllium, preferably impregnating beryllium into, onto, or with the alumina is hydrated beryllium nitrate. The most preferred beryllium component for incorporating beryllium, preferably impregnating beryllium into, onto, or with the alumina is beryllium nitrate trihydrate.
Examples of a potentially suitable cobalt component for incorporating cobalt, preferably impregnating cobalt into, onto, or with the alumina include, but are not limited to, cobalt nitrate hexahydrate, hydrated cobalt nitrate, cobalt chloride, hydrated cobalt chloride, cobalt chloride hexahydrate, cobalt chloride hydrate, cobalt acetate tetrahydrate, cobalt acetylacetonate, cobalt acetylacetonate hydrate, cobalt carbonate hydrate, cobalt perchlorate hexahydrate, hydrated cobalt sulfate, cobalt sulfate hydrate, and the like and combinations thereof. The preferred cobalt component for incorporating cobalt, preferably impregnating cobalt into, onto, or with the alumina is hydrated cobalt nitrate. The most preferred cobalt component for incorporating cobalt, preferably impregnating cobalt into, onto, or with the alumina is cobalt nitrate hexahydrate.
Examples of a potentially suitable iron component for incorporating iron, preferably impregnating iron into, onto, or with the alumina include, but are not limited to, iron nitrate nonahydrate, hydrated iron nitrate, iron chloride, hydrated iron chloride, iron chloride tetrahydrate, iron chloride hexahydrate, iron acetate, iron acetylacetonate, iron perchlorate hexahydrate, hydrated iron sulfate, iron sulfate heptahydrate, and the like and combinations thereof. The preferred iron component for incorporating iron, preferably impregnating iron into, onto, or with the alumina is hydrated iron nitrate. The most preferred iron component for incorporating iron, preferably impregnating iron into, onto, or with the alumina is iron nitrate nonahydrate.
Examples of a potentially suitable manganese component for incorporating manganese, preferably impregnating manganese into, onto, or with the alumina include, but are not limited to, manganese nitrate hexahydrate, hydrated manganese nitrate, manganese nitrate hydrate, manganese chloride, hydrated manganese chloride, manganese chloride tetrahydrate, manganese acetate dihydrate, manganese acetate tetrahydrate, manganese acetylacetonate, manganese carbonate, manganese perchlorate hexahydrate, hydrated manganese sulfate, manganese sulfate monohydrate, and the like and combinations thereof. The preferred manganese component for incorporating manganese, preferably impregnating manganese into, onto, or with the alumina is hydrated manganese nitrate. The most preferred manganese component for incorporating manganese, preferably impregnating manganese into, onto, or with the alumina is manganese nitrate hexahydrate.
Examples of a potentially suitable strontium component for incorporating strontium, preferably impregnating strontium into, onto, or with the alumina include, but are not limited to, strontium nitrate, hydrated strontium nitrate, strontium chloride, hydrated strontium chloride, strontium chloride hexahydrate, strontium acetate, strontium acetylacetonate, strontium carbonate, strontium perchlorate hydrate, hydrated strontium sulfate, strontium sulfate, and the like and combinations thereof. The preferred strontium component for incorporating strontium, preferably impregnating strontium into, onto, or with the alumina is strontium nitrate.
Examples of a potentially suitable lithium component for incorporating lithium, preferably impregnating lithium into, onto, or with the alumina include, but are not limited to, lithium nitrate, hydrated lithium nitrate, lithium chloride, hydrated lithium chloride, lithium chloride hydrate, lithium acetate dihydrate, lithium acetylacetonate, lithium perchlorate, lithium perchlorate trihydrate, lithium sulfate, lithium sulfate monohydrate, and the like and combinations thereof. The preferred lithium component for incorporating lithium, preferably impregnating lithium into, onto, or with the alumina is lithium nitrate.
Examples of a potentially suitable potassium component for incorporating potassium, preferably impregnating potassium into, onto, or with the alumina include, but are not limited to, potassium nitrate, hydrated potassium nitrate, potassium chloride, hydrated potassium chloride, potassium acetylacetonate hemihydrate, potassium carbonate sesquihydrate, potassium perchlorate, potassium sulfate, and the like and combinations thereof. The preferred potassium component for incorporating potassium, preferably impregnating potassium into, onto, or with the alumina is potassium nitrate.
The metal component(s) may be incorporated into, onto, or with the alumina by any suitable means or method(s) for incorporating the metal of such metal component(s) into, onto, or with a substrate material, such as alumina, which results in the formation of a metal-incorporated alumina which can then be dried and calcined to thereby provide a metal aluminate catalyst support. Examples of means or method(s) for incorporating include, but are not limited to, impregnating, soaking, spraying, and the like and combinations thereof. A preferred method of incorporating is impregnating using any standard incipient wetness impregnation technique (i.e., essentially completely filling the pores of the substrate material with a solution of the incorporating elements) for impregnating an alumina substrate with a metal component. A preferred method uses an impregnating solution comprising the desirable concentration of metal component so as to ultimately provide a metal-incorporated, preferably metal-impregnated, alumina which can then be subjected to drying and high temperature calcining to produce a metal aluminate catalyst support.
It can be desirable to use an aqueous solution of a metal component for the impregnation of the alumina. A preferred impregnating solution comprises an aqueous solution formed by dissolving a metal component, preferably such metal component is in the form of a metal salt, such as, but not limited to, a metal chloride, a metal nitrate, a metal sulfate, and the like and combinations thereof, in a solvent, such as, but not limited to, water, alcohols, esters, ethers, ketones, and the like and combinations thereof.
A preferred impregnating solution is formed by dissolving a metal component (such as zinc nitrate hexahydrate, magnesium nitrate hexahydrate, calcium nitrate tetrahydrate, barium nitrate, beryllium nitrate trihydrate, cobalt nitrate hexahydrate, iron nitrate nonahydrate, manganese nitrate hexahydrate, strontium nitrate, lithium nitrate, potassium nitrate, preferably, zinc nitrate hexahydrate) in water. It is acceptable to use somewhat of an acidic solution to aid in the dissolution of the metal component. It is preferred for the alumina to be impregnated with a zinc component by use of a solution containing zinc nitrate hexahydrate dissolved in water. In addition, magnesium nitrate hexahydrate or calcium nitrate tetrahydrate or barium nitrate or beryllium nitrate trihydrate or cobalt nitrate hexahydrate or iron nitrate nonahydrate or manganese nitrate hexahydrate or strontium nitrate or lithium nitrate or potassium nitrate can be used in place of zinc nitrate hexahydrate to impregnate the alumina with the metal of the respective metal component(s).
A more preferred method for incorporating a metal of a metal component into, onto, or with the alumina is to impregnate such alumina with a metal component which has been melted under a melting condition as described herein. Preferably such metal component is in the form of a metal salt, such as, but not limited to, a metal chloride, a metal nitrate, a metal sulfate, and the like and combinations thereof (such as, but not limited to, zinc nitrate hexahydrate, magnesium nitrate hexahydrate, calcium nitrate tetrahydrate, barium nitrate, beryllium nitrate trihydrate, cobalt nitrate hexahydrate, iron nitrate nonahydrate, manganese nitrate hexahydrate, strontium nitrate, lithium nitrate, potassium nitrate, and the like and combinations thereof, preferably, zinc nitrate hexahydrate). Addition of small amounts of an aqueous medium such as water to the metal component can be used to assist in the melting of such metal component.
Such melting condition includes a temperature below the decomposition temperature of the metal component for a time period and at a pressure that provides for a melted metal component, preferably a pourable melted metal component. The term xe2x80x9cdecomposition temperaturexe2x80x9d refers to the temperature at which the metal component is no longer soluble and is no longer suitable for incorporating, preferably impregnating, the metal of such metal component into, onto, or with alumina according to the inventive process(es) disclosed herein. The term xe2x80x9cpourable melted metal componentxe2x80x9d refers to a metal component that has been subjected to a melting condition and has become viscous enough to pour.
The temperature below the decomposition temperature of the metal component varies depending on the metal component but such temperature should be such as to provide a melted metal component. Such temperature is generally in the range of from about 25xc2x0 C. to about 160xc2x0 C., preferably in the range of from about 30xc2x0 C. to about 150xc2x0 C., more preferably in the range of from about 35xc2x0 C. to about 140xc2x0 C. and, most preferably, in the range of from 35xc2x0 C. to 130xc2x0 C.
Such melting condition can include a time period generally in the range of from about 1 minute to about 2 hours, preferably in the range of from about 5 minutes to about 1.5 hours and, most preferably, in the range of from 5 minutes to 1 hour. Such melting condition can include a pressure generally in the range of from about atmospheric (i.e., about 14.7 pounds per square inch absolute) to about 150 pounds per square inch absolute (psia), preferably in the range of from about atmospheric to about 100 psia, most preferably about atmospheric, so long as the desired temperature can be maintained.
The thus-melted metal component is then used to incorporate, preferably impregnate, the metal of such melted metal component into, onto, or with the alumina. The metal of such melted metal component is incorporated, preferably impregnated, into, onto, or with the alumina by adding such melted metal component to the alumina by pouring such melted metal component onto the surface of the alumina by any manner or method(s) which results in substantially all the surface area of the alumina being coated with the melted metal component. Preferably, such melted metal component is poured over the surface of the alumina while the alumina is under constant stirring or tumbling.
It can be desirable to pre-heat the alumina under a heating condition before such melted metal component is poured over the surface of the alumina. Such heating condition can include a temperature generally in the range of from about 80xc2x0 C. to about 150xc2x0 C., preferably in the range of from about 85xc2x0 C. to about 140xc2x0 C. and, most preferably, in the range of from 90xc2x0 C. to 130xc2x0 C. Such heating condition can include a time period generally in the range of from about 1 minute to about 2 hours, preferably in the range of from about 5 minutes to about 1.5 hours and, most preferably, in the range of from 5 minutes to 1 hour. Such heating condition can include a pressure generally in the range of from about atmospheric (i.e., about 14.7 pounds per square inch absolute) to about 150 pounds per square inch absolute (psia), preferably in the range of from about atmospheric to about 100 psia, most preferably about atmospheric, so long as the desired temperature can be maintained. The metal-incorporated, preferably metal-impregnated, alumina can be further heated near the melting point of the metal component for a time period in the range of from about 0.5 hour to about 15 hours, preferably in the range of from about 1 hour to about 8 hours and, most preferably, in the range of from 1 hour to 5 hours.
In a most preferred method, melted zinc nitrate hexahydrate is used to incorporate, preferably impregnate, the zinc of such melted zinc nitrate hexahydrate into, onto, or with the alumina. The zinc of such melted zinc nitrate hexahydrate is incorporated, preferably impregnated, into, onto, or with the alumina by adding such melted zinc nitrate hexahydrate to the alumina by pouring such melted zinc nitrate hexahydrate onto the surface of the alumina by any manner or method(s) which results in substantially all the surface area of the alumina being coated with the melted zinc nitrate hexahydrate. Preferably, such melted zinc nitrate hexahydrate is poured over the surface of the alumina while the alumina is under constant stirring or tumbling. In addition, magnesium nitrate hexahydrate or calcium nitrate tetrahydrate or barium nitrate or beryllium nitrate trihydrate or cobalt nitrate hexahydrate or iron nitrate nonahydrate or manganese nitrate hexahydrate or strontium nitrate or lithium nitrate or potassium nitrate can be used in place of zinc nitrate hexahydrate to incorporate, preferably impregnate, the metal of such metal component(s) into, onto, or with the alumina in the same above-described manner as for incorporating, preferably impregnating, the zinc of such zinc nitrate hexahydrate.
Generally, the amount of metal component, preferably zinc component, incorporated, preferably impregnated, into, onto, or with the alumina is an amount which provides, after the metal-incorporated alumina has been dried and calcined according to the inventive process(es) disclosed herein, a metal aluminate catalyst support having an amount of metal aluminate generally in the range of from about 1 weight percent of the total weight of the metal aluminate catalyst support to about 100 weight percent. Preferably the amount of metal in, on, or with the metal-incorporated alumina is in an amount which provides a metal aluminate catalyst support having an amount of metal aluminate in the range of from about 15 weight percent of the total weight of the metal aluminate catalyst support to about 75 weight percent and, most preferably, in the range of from 25 weight percent to 65 weight percent.
The metal-incorporated alumina can then be dried under a drying condition. Generally, such drying condition can include a temperature in the range of from about 80xc2x0 C. to about 140xc2x0 C., preferably in the range of from about 90xc2x0 C. to about 130xc2x0 C. and, most preferably, in the range of from 100xc2x0 C. to 120 xc2x0 C. Such drying condition can also include a time period for drying the metal-incorporated alumina generally in the range of from about 0.5 hour to about 60 hours, preferably in the range of from about 1 hour to about 40 hours and, most preferably, in the range of from 1.5 hours to 20 hours to produce a dried metal-incorporated alumina. Such drying condition can also include a pressure generally in the range of from about atmospheric (i.e., about 14.7 pounds per square inch absolute) to about 150 pounds per square inch absolute (psia), preferably in the range of from about atmospheric to about 100 psia, most preferably about atmospheric, so long as the desired temperature can be maintained. Any drying method(s) known to one skilled in the art such as, for example, air drying, heat drying, and the like and combinations thereof can be used.
The thus-dried metal-incorporated alumina can then be calcined under a calcining condition to thereby provide a metal aluminate catalyst support. The calcining condition is important in providing a metal aluminate catalyst support having physical characteristics, such as, for example, a surface area, pore volume, average pore diameter, and crystalline domain size, in the ranges as disclosed herein, suitable for using such metal aluminate catalyst support as a support for hydrogenation and dehydrogenation catalysts.
Generally, such calcining condition can include a temperature in the range of from about 600xc2x0 C. to about 1350xc2x0 C., preferably in the range of from about 675xc2x0 C. to about 1300xc2x0 C., more preferably, in the range of from about 800xc2x0 C. to about 1250xc2x0 C. and, most preferably, in the range of from 900xc2x0 C. to 1200xc2x0 C. Such calcining condition can also include a pressure, generally in the range of from about 7 pounds per square inch absolute (psia) to about 750 psia, preferably in the range of from about 7 psia to about 450 psia and, most preferably, in the range of from 7 psia to 150 psia, and a time period in the range of from about 1 hour to about 60 hours, preferably for a time period in the range of from about 2 hours to about 20 hours and, most preferably, for a time period in the range of from 3 hours to 15 hours.
Upon calcination of the dried metal-incorporated alumina, a metal aluminate will form in, on the outside surface of, or on, but not limited to, the surface of, the alumina to thereby provide a metal aluminate catalyst support of the invention. Examples of a suitable metal aluminate include, but are not limited to, a zinc aluminate, also referred to as a zinc spinel, a magnesium aluminate, also referred to as a magnesium spinel, a calcium aluminate, also referred to as a calcium spinel, a barium aluminate, also referred to as a barium spinel, a beryllium aluminate, also referred to as a beryllium spinel, a cobalt aluminate, also referred to as a cobalt spinel, an iron aluminate, also referred to as an iron spinel, a manganese aluminate, also referred to as a manganese spinel, a strontium aluminate, also referred to as a strontium spinel, a lithium aluminate, also referred to as a lithium spinel, a potassium aluminate, also referred to as a potassium spinel, and the like and combinations thereof. A preferred metal aluminate is selected from the group consisting of a zinc aluminate, also referred to as a zinc spinel, a magnesium aluminate, also referred to as a magnesium spinel, a calcium aluminate, also referred to as a calcium spinel, and the like and combinations thereof. A more preferred metal aluminate is a zinc aluminate, also referred to as a zinc spinel.
The amount of metal aluminate of the metal aluminate catalyst support, preferably zinc aluminate catalyst support, is generally in the range of from about 1 weight percent based on the total weight of the metal aluminate catalyst support to about 100 weight percent. Preferably, the amount of metal aluminate of the metal aluminate catalyst support of the invention is in the range of from about 15 weight percent based on the total weight of the metal aluminate catalyst support to about 75 weight percent and, most preferably, in the range of from 25 weight percent to 65 weight percent.
The amount of alpha alumina of the metal aluminate catalyst support, preferably zinc aluminate catalyst support, is generally in the range of from about 0 weight percent based on the total weight of the metal aluminate catalyst support to about 99 weight percent, preferably in the range of from about 10 weight percent to about 85 weight percent and, most preferably, in the range of from 15 weight percent to 70 weight percent. The crystalline domain size of the alpha alumina of the metal aluminate catalyst support is generally in the range of from about 25 angstroms to about 3000 angstroms, preferably in the range of from about 25 angstroms to about 2500 angstroms and, most preferably, in the range of from 50 angstroms to 2000 angstroms. The xe2x80x9ccrystalline domain sizexe2x80x9d is determined from the line broadening of the X-ray diffraction profile.
The amount of gamma alumina of the metal aluminate catalyst support, preferably zinc aluminate catalyst support, generally ranges upwardly from about 0 weight percent based on the total weight of the metal aluminate catalyst support to about 60 weight percent, preferably in the range of from about 0 weight percent to about 50 weight percent and, most preferably, in the range of from 0 weight percent to 40 weight percent.
Generally, the surface area of the metal aluminate catalyst support, preferably zinc aluminate catalyst support, is in the range of from about 1 m2/g (measured by the Brunauer, Emmett, Teller method, i.e. BET method) to about 200 m2/g, preferably in the range of from about 1 m2/g to about 150 m2/g, more preferably in the range of from about 5 m2/g to about 125 m2/g and, most preferably, in the range of from 10 m2/g to 80 m2/g.
The pore volume of the metal aluminate catalyst support, preferably zinc aluminate catalyst support, is generally in the range of from about 0.05 mL/g to about 2 mL/g, preferably in the range of from about 0.10 mL/g to about 1.5 mL/g and, most preferably, in the range of from 0.10 mL/g to 1 mL/g.
The average pore diameter of the metal aluminate catalyst support, preferably zinc aluminate catalyst support, is generally in the range of from about 50 angstroms to about 1000 angstroms, preferably in the range of from about 50 angstroms to about 750 angstroms and, most preferably, in the range of from 50 angstroms to 450 angstroms.
The crystalline domain size of the metal aluminate, preferably zinc aluminate, of the metal aluminate catalyst support is generally in the range of from about 25 angstroms to about 1750 angstroms, preferably in the range of from about 25 angstroms to about 1500 angstroms, more preferably in the range of from about 25 angstroms to about 1250 angstroms and, most preferably, in the range of from 25 angstroms to 1000 angstroms.
The particle size of the metal aluminate catalyst support, preferably zinc aluminate catalyst support, is generally in the range of from about 0.5 millimeter (mm) to about 10 mm, preferably in the range of from about 1 mm to about 8 mm and, most preferably, in the range of from 1 mm to 6 mm.
The metal aluminate catalyst support, preferably zinc aluminate catalyst support, prepared by the inventive process(es) described herein can be used as a catalyst support in the selective hydrogenation processes described in, for example, U.S. Pat. Nos. 5,510,550; 5,475,173; and 5,583,274. The metal aluminate catalyst support, preferably zinc aluminate catalyst support, prepared by the inventive process described herein can also be used as a catalyst support for a dehydrogenation process such as the process described in, for example, U.S. Pat. No. 3,641,182.
The following examples are presented to further illustrate the invention and are not to be considered as unduly limiting the scope of the invention.